Simple C# - Interactive

using System.Windows.Forms;
using System.Drawing;

public class Simple : Form
{
    public Simple()
    {
       Text = "Simple";
       Size = new Size(250, 200);
       CenterToScreen();
    }

    static public void Main()
    {
       Application.Run(new Simple());
    }
}

Save as Simple.cs

[greg:mono] gmcs -r:System.Windows.Forms.dll -r:System.Drawing.dll Simple.cs
[greg:mono] mono Simple.exe

The latest release of Mono is the first version to support the ASP.NET MVC framework.